Southwest Amazon moist forests

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Southwest Amazon moist forests (NT0166)
Uakari male.jpg
One of the rare species of the ecoregion, the bald uakari (Cacajao calvus) is restricted to várzea forests and other wooded habitats near water in the western Amazon rainforest of Brazil and Peru. [1]
Ecoregion NT0166.svg
Location in South America
Ecology
Realm Neotropical
Biome Tropical and subtropical moist broadleaf forests
Geography
Area749,800 km2 (289,500 sq mi)
Countries Peru, Brazil, Bolivia
Coordinates 10°10′25″S71°30′55″W / 10.173527°S 71.515218°W / -10.173527; -71.515218
Climate typeAm: equatorial, monsoonal

The Southwest Amazon moist forests (NT0166) is an ecoregion located in the Upper Amazon basin.

Contents

The forest is characterized by a relatively flat landscape with alluvial plains dissected by undulating hills or high terraces. [2] The biota of the southwest Amazon moist forest is very rich because of these dramatic edaphic and topographical variations at both the local and regional levels. This ecoregion has the highest number of both mammals and birds recorded for the Amazonian biogeographic realm: 257 with 11 endemic species for mammals and 782 and 17 endemics for birds. The inaccessibility of this region, along with few roads, has kept most of the habitat intact. Also, there are a number of protected areas, which preserve this extremely biologically rich ecoregion.

Location

Mauritia flexuosa, or moriche palm, is an economically important species dominant in some parts of the ecoregion. Buriti.JPG
Mauritia flexuosa, or moriche palm, is an economically important species dominant in some parts of the ecoregion.

The southwest Amazon moist forest region covers an extensive area of the Upper Amazon Basin comprising four sub-basins: (1) both the Pastaza-Marañon and (2) Ucayali River sub-basins drain into the Upper Amazon River in Peru; (3) the Acre and (4) Madre de Dios-Beni sub-basins drain to the east into the Juruá, Purus and Madeira Rivers; which, in turn, feed into the Amazon River lower down in Brazil. [2] The region is bisected north to south between Peru and Brazil by the small mountain range Serra do Divisor. It extends east to the edge of the Purus Arch, or ancient zone of uplift, in the southwestern area of the Brazilian State of Amazonas. It then extends southeast into northern Bolivia and in a narrow band south along the base of the Andes Mountains. Elevations range from 300 metres (980 ft) in the west to 100 metres (330 ft) on the eastern edge of the region.

Landforms present in this region include the upland terra firme (non-flooded) mostly on nutrient-poor lateritic soils, ancient alluvial plains (mostly non-flooded) on nutrient-rich soils, and present alluvial plains (várzea, seasonally flooded) of super-rich sediments renewed with each annual flood. [2] Floristically, distinct lowland humid forest types occur on each of these landforms with the terra firme mature forests and late successional, seasonally flooded forest being the two major types. Permanent swamp forests are common on the alluvial plains. Pockets of nutrient-poor white sand soils are found here that host forests of lower height, a more open forest canopy, and lower alpha diversity, but with many endemics. The forests are mostly dense tropical rain forest, but some patches of open forest exist.

The ecoregion contains stretches of Iquitos várzea along the main rivers, blending into Purus várzea near the eastern border, where it adjoins the Juruá–Purus moist forests ecoregion. In the southeast, it adjoins the Purus–Madeira moist forests and Madeira–Tapajós moist forests, and in the south merges into the Beni savanna and Bolivian Yungas. In the southwest, it adjoins the Peruvian Yungas. To the west, it adjoins the Ucayali moist forests. In the north it is separated by a band of Iquitos varzea from the Solimões–Japurá moist forests. [3]

General description of flora

Because the ecoregion covers such a vast area, there are climatic, edaphic and floristic differences within it. Generally, the wetter and less seasonal northern forests (3,000 millimetres (120 in) of rain annually) share only 44 percent of the tree species with forests in the slightly drier, more seasonal southern region. This region receives from 1,500 to 2,100 millimetres (59 to 83 in) of rain annually, in different parts. Temperatures over the year range from 22 to 27 °C (72 to 81 °F).

At first glance, large areas may appear to be homogeneous dense forests with a canopy 30 to 40 metres (98 to 131 ft) high with some emergent trees to 50 metres (160 ft) towering above the canopy. [2] Structurally, this may be the case; however, the species composition reflects much the opposite: tree species variability reaches upwards to 300 species in a single hectare. There are a few exceptions to this high diversity, mainly where stands dominated by one or several species occur. The first are vast areas (more than 180,000 square kilometres (69,000 sq mi)) dominated by the highly competitive arborescent bamboos Guadua sarcocarpa and Guadua weberbaueri near Acre, Brazil extending into Peru and Bolivia. Other monodominant stands include swamp forests of the economically important palms Mauritia flexuosa and Jessenia bataua .

In the north of the region, some of the best known plants yield products of commercial value, such as rubber ( Hevea brasiliensis ), mahogany ( Swietenia macrophylla ), balsam wood ( Myroxylon balsamum ), timber and essential oil ( Amburana acreana ), tagua nut ( Phytelephas microcarpa ), and strychnine ( Strychnos asperula ). [2] An area representative of the southern part of this region, in the north of Bolivia, hosts a seasonal humid high forest to 35 metres (115 ft) with some emergents reaching 40 metres (130 ft) in height and many buttressed trunks. The largest trees are Ceiba pentandra , Poulsenia armata , Calycophyllum spruceanum , Swietenia macrophylla , and Dipteryx odorata . Other trees typical in this area are Calycophyllum acreanum , Terminalia amazonica , Combretum laxum , Mezilaurus itauba , Didymopanax morototoni , Jacaranda copaia , Aspidosperma megalocarpon , Vochisia vismiaefolia , Hirtella lightioides , and Hura crepitans . Palms include, among others, members of the genera Astrocaryum , Iriartea and Sheelea , Oenocarpus mapora , Chelyocarpus chuco , Phytelephas macrocarpa , Euterpe precatoria , and Jessenia bataua . Lianas are common with about 43 species present. Many Amazonian species reach the southern limit of their distribution here. The Brazil nut tree ( Bertholletia excelsa ) is present in the south, but is likely not native this far west in Amazonia.

Biodiversity features

Leopardus pardalis, the ocelot, is a threatened species that finds a home in the southwest Amazon moist forests. Ocelot (Leopardus pardalis)-8.jpg
Leopardus pardalis, the ocelot, is a threatened species that finds a home in the southwest Amazon moist forests.

What is distinctive about this region is the diversity of habitats created by edaphic, topographic and climatic variability. Habitat heterogeneity, along with a complex geological and climatic history has led to a high cumulative biotic richness. Endemism and overall richness is high in vascular plants, invertebrates and vertebrate animals. [2] This is the Amazon Basin's center of diversity for palms. The rare palm Itaya amicorum is found on the upper Javari River. This ecoregion has the highest number of mammals recorded for the Amazonian biogeographic realm: 257 with 11 endemics. Bird richness is also highest here with 782 species and 17 endemics. In the southern part of the Tambopata Reserve, one area that is 50 square kilometres (19 sq mi) holds the record for bird species: 554. On the white sand areas in the north, plants endemic to this soil type include Jacqueshuberia loretensis , Ambelania occidentalis , Spathelia terminalioides , and Hirtella revillae .

Many widespread Amazonian mammals and reptiles find a home in this region. [2] These include tapirs ( Tapirus terrestris ), jaguars ( Panthera onca ), the world's largest living rodents, capybaras ( Hydrochoerus hydrochaeris ), kinkajous ( Potos flavus ), and white-lipped peccaries ( Tayassu pecari ). Some of the globally threatened animals found in this region include black caimans ( Melanosuchus niger ) and spectacled caimans ( Caiman crocodilus crocodilus ), woolly monkeys ( Lagothrix lagotricha ), giant otters ( Pteronura brasiliensis ), giant anteaters ( Myrmecophaga tridactyla ), and ocelots ( Leopardus pardalis ).

Pygmy marmosets ( Cebuella pygmaea ), Goeldi marmosets ( Callimico goeldii ), pacaranas ( Dinomys branickii ), and eastern lowland olingos ( Bassaricyon alleni ) are found here, but not in regions to the east. [2] [4] Other primates present include tamarins ( Saguinus fuscicollis and Saguinus imperator ), brown pale-fronted capuchins ( Cebus albifrons ), squirrel monkeys ( Saimiri sciureus ), white-faced sakis ( Pithecia irrorata ), and black spider monkeys ( Ateles paniscus ). The rare red uakari monkeys ( Cacajao calvus ) are found in the north in swamp forests. Nocturnal two-toed sloths ( Choloepus hoffmanni ) are well distributed throughout this region along with the widespread three-toes sloths ( Bradypus variegatus ). The Amazon River is a barrier to a number of animals such as the tamarins Saguinus nigricollis , which occur on the north side, and Saguinus mystax , which occurs on the southwest side of the Amazon-Ucayali system.

In the region of Manu, 68 species of reptiles and 68 species of amphibians have been reported for the lowland areas while 113 species of amphibians and 118 species of reptiles are reported from Madre de Dios, including the rare and interesting pit-vipers ( Bothrops bilineatus , Bothrops brazili ), and frogs such as Dendrophidion sp. , Rhadinaea occipitalis , and Xenopholis scalaris . [2]

Current status

The riverbank of Manu National Park. Manu riverbank.jpg
The riverbank of Manú National Park.

Much of the natural habitat of the region remains intact, protected by sheer inaccessibility. [2] People have dwelled along the major rivers for millennia and have subtly altered the forests on a small scale, but around the urban centers development proceeds. Very few roads exist in the region, limiting development. Intense deforestation is constrained to the few roads that do exist or around urban centers such as Iquitos, Puerto Maldonado, and Rio Branco.

Manú National Park, a World Heritage Site, protects 15,328 square kilometres (5,918 sq mi) of pristine lowland forest in southern Peru, a large part of which falls into this ecoregion. [2] The nearby Tambopata-Candamo reserve protects seven major forest types. This reserve offers refuge to game species that have been over-hunted in other areas such as tapirs, spider monkeys, jaguars, capybaras, white-lipped peccaries, monkeys, caimans and river turtles. The Manuripi-Heath Amazonian Wildlife National Reserve is located in the southernmost area of this region in Bolivia covering 18,900 square kilometres (7,300 sq mi) of dense tropical forest. Several extractive reserves, the largest being Chico Mendes Extractive Reserve and Alto Juruá Extractive Reserve, are actively managed in Brazil. Other protected areas include national parks (Serra do Divisor National Park, Madidi National Park, Isoboro Secure National Park, Bahuaja-Sonene National Park), national forests, Rio Acre Ecological Station, Antimari State Forest, Apurimac Reserve Zone, among others. Most protected areas suffer from insufficient administration and patrol.

Types and severity of threats

The invasive Guadua bamboo is threatening the natural ecodiversity of the region. Guadua-Bambus-Colombia.jpg
The invasive Guadua bamboo is threatening the natural ecodiversity of the region.

Hunting may be threatening populations of the tapir ( Tapirus terrestris ) and large primates in the north. [2] Some habitat is threatened by expansion of the agricultural and pastoral frontier, gold mining, and selective logging that erodes the genetic diversity of a few valuable timber species. The economically important palm Euterpe precatoria is being depleted in some areas by unsustainable palm heart extraction. A dramatic problem that exists in the Brazilian State of Acre and in the adjacent area of Peru is the spread of the invasive Guadua bamboo forests. This highly competitive bamboo invades and dominates abandoned clearings and threatens to dominate the disturbed areas in this region. Logging along major rivers and near urban centers has decimated populations of mahogany ( Swietenia macrophylla ), tropical cedar ( Cedrela odorata ), and kapok ( Ceiba pentandra ).

During the period from 2004 to 2011 the ecoregion experienced an annual rate of habitat loss of 0.17%. [5]

Related Research Articles

<span class="mw-page-title-main">Purus River</span> River in Brazil, Peru

The Purus River is a tributary of the Amazon River in South America. Its drainage basin is 371,042 km2 (143,260 sq mi), and the mean annual discharge is 11,207 m3/s (395,800 cu ft/s). The river shares its name with the Alto Purús National Park and the Purús Province, one of the four provinces of Peru in the Ucayali Region.

The Mamirauá Sustainable Development Reserve in the Brazilian state of Amazonas, near the city of Tefé, is a 4,300-square-mile (11,000 km2) reserve near the village of Boca do Mamirauá. It includes mostly Amazonian flooded forest and wetlands. The ribeirinhos are native to the area.

A várzea forest is a seasonal floodplain forest inundated by whitewater rivers that occurs in the Amazon biome. Until the late 1970s, the definition was less clear and várzea was often used for all periodically flooded Amazonian forests.

<span class="mw-page-title-main">Amazon biome</span> Ecological region of South America

The Amazon biome contains the Amazon rainforest, an area of tropical rainforest, and other ecoregions that cover most of the Amazon basin and some adjacent areas to the north and east. The biome contains blackwater and whitewater flooded forest, lowland and montane terra firma forest, bamboo and palm forest, savanna, sandy heath and alpine tundra. Some areas of the biome are threatened by deforestation for timber and to make way for pasture or soybean plantations.

<span class="mw-page-title-main">Tamshiyacu Tahuayo Regional Conservation Area</span>

Tamshiyacu Tahuayo Regional Conservation Area is a protected area located south east of Iquitos, extending over the Peruvian department of Loreto, provinces of Maynas, Ramón Castilla and Requena. It was established by the Peruvian Ministry of Environment on May 15, 2009. The reserve is managed and funded by the Regional Government of Loreto.

<span class="mw-page-title-main">Campinarana</span> Open shrubland and savanna in the north of Brazil and in Colombia and Venezuela

Campinarana, also called Rio Negro Campinarana, is a neotropical ecoregion in the Amazon biome of the north west of Brazil and the east of Colombia that contains vegetation adapted to extremely poor soil. It includes savanna, scrub and forest, and contains many endemic species of fauna and flora.

<span class="mw-page-title-main">Japurá–Solimões–Negro moist forests</span> Ecoregion in the Amazon Biome

The Japurá–Solimões–Negro moist forests (NT0132) is an ecoregion of tropical moist broad leaf forest in the Amazon biome.

<span class="mw-page-title-main">Monte Alegre várzea</span> Ecoregion in Brazil

The Monte Alegre várzea (NT0141) is an ecoregion of seasonally flooded várzea forest along the Amazon River in the Amazon biome.

<span class="mw-page-title-main">Purus várzea</span> Ecoregion in the Amazon biome

The Purus várzea (NT0156) is an ecoregion of seasonally flooded várzea forest in the central Amazon basin. It is part of the Amazon biome. The ecoregion is home to a vegetation adapted to floods of up to 12 metres (39 ft) that may last for eight months. There is a great variety of fish and birds, but relatively fewer mammals. Ground-dwelling mammals must migrate to higher ground during the flood season. Threats include logging, cattle farming, over-fishing and mercury pollution from gold mining.

<span class="mw-page-title-main">Purus–Madeira moist forests</span> Ecoregion in the Amazon biome

The Purus-Madeira moist forests (NT0157) is an ecoregion in the central Amazon basin. It is part of the Amazon biome. The ecoregion covers a stretch of flat and relatively infertile land between the Purus and Madeira rivers, extending to the Solimões River in the north. It is isolated from other regions by the seasonally flooded várzea forest along these rivers, and has a high degree of endemism among its flora and fauna. The natural environment is relatively intact. The BR-319 highway was built along the length of the ecoregion in the early 1970s, but rapidly deteriorated and is now closed.

<span class="mw-page-title-main">Madeira–Tapajós moist forests</span> Ecoregion in the Amazon

The Madeira-Tapajós moist forests (NT0135) is an ecoregion in the Amazon basin. It is part of the Amazon biome. The ecoregion extends southwest from the Amazon River between its large Madeira and Tapajós tributaries, and crosses the border into Bolivia. In the south it transitions into the cerrado biome of Mato Grosso. In the state of Rondônia it contains some of the most degraded land of the Amazon basin.

<span class="mw-page-title-main">Tapajós–Xingu moist forests</span>

The Tapajós–Xingu moist forests (NT0168) is an ecoregion in the eastern Amazon basin. It is part of the Amazon biome. The ecoregion extends southwest from the Amazon River between its large Tapajós and Xingu tributaries.

<span class="mw-page-title-main">Xingu–Tocantins–Araguaia moist forests</span>

The Xingu–Tocantins–Araguaia moist forests (NT0180) is an ecoregion in the eastern Amazon basin. It is part of the Amazon biome. The ecoregion is one of the most severely degraded of the Amazon region, suffering from large-scale deforestation and selective extraction of timber, particularly along the Trans-Amazonian Highway and in the higher and more populated southern portions.

<span class="mw-page-title-main">Tocantins–Araguaia–Maranhão moist forests</span>

The Tocantins–Araguaia–Maranhão moist forests (NT0170), also called the Tocantins/Pindaré moist forests, is an ecoregion in the north of Brazil to the south of the mouth of the Amazon River. It is part of the Amazon biome. The ecoregion contains the city of Belém, capital of the state of Pará. It is the most developed part of the Amazon region, and is one of the most severely degraded natural habitats of the region.

<span class="mw-page-title-main">Solimões–Japurá moist forests</span> Ecoregion in the Amazon biome

The Solimões-Japurá moist forests (NT0163) is an ecoregion in northwest Brazil and eastern Peru and Colombia in the Amazon biome. It has a hot climate with high rainfall throughout the year, and holds one of the most diverse collections of fauna and flora in the world. The ecoregion is relatively intact.

<span class="mw-page-title-main">Iquitos várzea</span>

The Iquitos várzea (NT0128) is an ecoregion of flooded forest along rivers in Brazil, Peru and Bolivia in the west of the Amazon biome. The forest is seasonally flooded up to 7 metres (23 ft) by whitewater rivers carrying nutrient-rich sediment from the Andes. The meandering rivers often shift course, creating a complex landscape of oxbow lakes, marshes, levees and bars, with grasslands, shrubs and forests in different stages of succession. During the extended flood periods fish enter the forest in search of fruit. The várzea is accessible by the navigable rivers that run through it, and has suffered from extensive deforestation to extract timber and create pasture for livestock.

<span class="mw-page-title-main">Juruá–Purus moist forests</span> Ecoregion in the Amazon biome

The Juruá–Purus moist forests (NT0133) is an ecoregion in northwest Brazil in the Amazon biome. The terrain is very flat and soils are poor. The rivers flood annually. There are no roads in the region, and the dense rainforest is relatively intact, although plans to extend the Trans-Amazonian Highway through the region would presumably cause widespread damage to the habitat.

<span class="mw-page-title-main">Uatuma–Trombetas moist forests</span>

The Uatuma–Trombetas moist forests (NT0173) is an ecoregion in northwest Brazil in the Amazon biome. It covers the Amazon basin north of the Amazon River from close to the Atlantic Ocean to the Rio Negro west of Manaus. The ecoregion is relatively intact, although it has been damaged along the main rivers and around population centers.

<span class="mw-page-title-main">Napo moist forests</span>

The Napo moist forests (NT0142) is an ecoregion in the western Amazon rainforest of Colombia, Ecuador and Peru.

References

As of this edit, this article uses content from "Southwest Amazon moist forests" , which is licensed in a way that permits reuse under the Creative Commons Attribution-ShareAlike 3.0 Unported License, but not under the GFDL. All relevant terms must be followed.

  1. Veiga, L. M.; Bowler, M.; Silva Jr., J. S.; Queiroz, H. L.; Boubli, J.-P. & Rylands, A. B. (2008). "Cacajao calvus". IUCN Red List of Threatened Species . 2008: e.T3416A9846330. doi: 10.2305/IUCN.UK.2008.RLTS.T3416A9846330.en .
  2. 1 2 3 4 5 6 7 8 9 10 11 12 World Wildlife Fund (26 August 2008). "Southwest Amazon moist forests". In Mark McGinley (ed.). Encyclopedia of Earth . Retrieved 11 April 2011.
  3. WildFinder – WWF.
  4. Helgen, K. M.; Pinto, M.; Kays, R.; Helgen, L.; Tsuchiya, M.; Quinn, A.; Wilson, D.; Maldonado, J. (15 August 2013). "Taxonomic revision of the olingos (Bassaricyon), with description of a new species, the Olinguito". ZooKeys (324): 1–83. doi: 10.3897/zookeys.324.5827 . PMC   3760134 . PMID   24003317.
  5. Coca-Castro et al. 2013, p. 12.

Sources

Further reading